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Technical Highlights |
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To understand how the DonSPEED Racing
muffler works, you must first understand how one exhaust
system can generate more horsepower and torque than
another. The ability of the exhaust system to maintain
exhaust velocity has a tremendous impact on realizing
maximum horsepower and torque. Any significant changes
in the exhaust system, such as mufflers or collectors
will have an impact on exhaust gas velocity. The large
area change seen at the transition of the primary tube
to the muffler causes an immediate reduction of exhaust
gas speed. This reduction in speed decreases the
efficiency of the exhaust system, thereby reducing the
exhaust system’s scavenging ability. Further more, as
the exhaust exits the muffler/collector and enters the
atmosphere, a reverse pressure wave is generated that
returns back up into the exhaust system. Since the gas
speed in the muffler/collector is so low, it’s ability
to overcome this pressure wave is reduced. This
increases the turbulence in the muffler/collector and
further reduces the exhaust system’s efficiency. The
ability of an exhaust system to scavenge spent gasses
from the combustion chamber, and to assist in the
introduction of fresh mixture into the cylinder during
the exhaust/intake overlap period is what makes one
exhaust system better that another one. The object is to
get as much of the fresh air/fuel mixture into the
cylinder than would otherwise be possible by relying
solely on atmosphere pressure alone. When the exhaust
system is designed correctly for the given application,
we can achieve volumetric efficiency levels over 100%.
This provides us with more power and better drivability.
This increase in efficiency also provides us better fuel
mileage and lower emissions, since fuel that would be
unused and left in the intake or exhaust system is used
and burned completely. The "Torque-Cone" at the exit
of the muffler does a couple of things:
- Due to it’s cone shape, the Torque-Cone
provides the free flow of exhaust gasses as they
exit the exhaust system, but the back flow of the
reverse pressure waves is inhibited as it tries to
re-enter the exhaust system. The positioning of the
"Torque-Cone" at the muffler/collector’s outlet also
allows the effective outlet area of the
muffler/collector to be precisely calibrated to
match the exhaust system’s flow requirements. This
provides the optimum balance of flow and velocity
for maximum performance.
- The cone shape resists and helps to dissipate
the reverse pressure wave as it attempts to re-enter
the exhaust system.
Both the increase in gas speed, and the reduction in
reverse pressure waves, reduces the turbulence present
in the muffler/collector due to the drop in velocity as
the gas leaves the primary tube providing and increase
in horsepower and torque across the entire powerband.
Many devices are employed in an attempt to increase
exhaust velocity and reduce turbulence in the name of
"Back-Pressure", but most of them are only devices
masking a design flaw in the exhaust system. DonSPEED
Racing mufflers ( Lightning)
are the only mufflers that are engineered as a complete
system. |
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Lightning Racing Mufflers Div. DonSPEED Racing
3319 Fitzgerald Road, Suite 12,
Rancho Cordova, CA 95742
Tel: 1-(916) 853-9738 |
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